[ARC5] Select-O-Ject

[William Cromwell]

Hi Richard,

I have been a fan of the Select-O-Ject AND the Q multiplier. The S-O-J 
definitely works in the audio section. I started gathering parts to 
build one a number of years ago when I noticed the switched capacitor 
audio filters with most of the features of the S-O-J. I am not sure the 
switched cap can be set to serve as an oscillator (but maybe). The other 
features of the S-O-J are all there. I went down that street. My 
switched  cap filter is manually controlled with front panel knobs and 
switches the same way as the S-O-J. If I ever find a S-O-J at a hamfest 
with a reasonable askit I will bring it home.

Q multipliers might be less complicated at IF frequencies in multiband 
receivers but used ahead of the first mixer in the front end help with 
image performance. They can also be easily overloaded. Using that kind 
of technology requires us to actually operate the radio instead of 
having some computer do it all for us:) Isn't that a *feature* of 
playing with boat anchors?

73,

Bill KU8H

bark less - wag more

On 8/18/21 2:55 AM, Richard Knoppow wrote:
> I got into a discussion on some mailing list about the Selectoject. I 
> said it worked at audio frequencies and others insisted it worked at 
> RF (in the IF actually). I have no memory of which list this was on 
> and can't find it.
> In any case I found the original article by Villard and Weaver in the 
> November, 1949 edition of QST, p.11. It does work at audio. The 
> subtitle is: The Selectoject, a variable frequency selective audio 
> amplifier, oscillator, and rejection filter. If I didn't post here 
> perhaps it will still be of some interest.
>    I think there was confusion with a Q-multiplier. While in principle 
> a Q-multiplier can work at any frequency most were built to work in 
> the IF of a receiver.
>